P87LPC778 datasheet(68/79 Pages) PHILIPS

68 / 79 page

Philips Semiconductors

P87LPC778

CMOS single-chip 8-bit microcontroller

Product data

Rev. 01 — 31 March 2004

68 of 79

9397 750 12378

8.18.2

Security bits

When neither of the security bits are programmed, the code in the EPROM can be verified.

When only security bit 1 is programmed, all further programming of the EPROM is disabled. At

that point, only security bit 2 may still be programmed. When both security bits are

programmed, EPROM verify is also disabled.

0 1 0

Low frequency crystal, 20 kHz to 100 kHz.

0 0 1

Medium frequency crystal or resonator, 100 kHz to 4 MHz.

0 0 0

High frequency crystal or resonator, 4 MHz to 20 MHz.

Table 63:

UCFG2 - EPROM system conﬁguration byte 2 register (address FD01H) bit

allocation

Unprogrammed value: FFH

Bit

Symbol

SB2

SB1

Table 64:

UCFG2 - EPROM system conﬁguration byte 2 register (address FD01H) bit

description

Bit

Symbol

Description

7, 6

SB2, SB1

EPROM security bits. See Table 65 for details.

5 to 0

Reserved for future use.

Table 62:

FOSC2-FOSC0 oscillator conﬁguration…continued

FOSC[2:0]

Oscillator conﬁguration

Table 65:

EPROM security bits

SB2

SB1

Protection description

Both security bits unprogrammed. No program security

features enabled. EPROM is programmable and

verifiable.

Only security bit 1 programmed. Further EPROM

programming is disabled. Security bit 2 may still be

programmed.

Only security bit 2 programmed. This combination is

not supported.

Both security bits programmed. All EPROM verification

and programming are disabled.

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